92 MAINE AGRICULTURAL EXPERIMENT STATION. I904. 



protected in the same way — the stigmas were never exposed 

 except for the moment when pollen was applied to them. 



Other methods of protecting the flowers were tried, such as 

 covering with paper bags and glass bell- jars, but were found less 

 satisfactory owing to the fact that a close atmosphere for the 

 entire flower seemed to hasten decay of the pistils, thus shorten- 

 ing the age of the flower and giving less time for the action of 

 pollen. No pollen was used that was more than twenty-four 

 hours old; and all pistils were discarded, which, because of age 

 or structure, were unfit for pollination work. 



By actual count, 284 pistils of crookneck squash were polli- 

 nated with golden custard. Of this number about one-third 

 were picked off at various stages, and preserved for microscop- 

 ical study. The rest were left on the vines as long as they 

 remained intact. As would be expected in any case of artificial 

 pollination, a large number of the crosses were a complete fail- 

 ure, as was evidenced by the early death of all parts of the 

 flower. In a few cases, however, the ovary made an unusual 

 growth, due, it was thought, to the scarcity of blossoms, and to 

 the vigor of the plants ; and as interesting results were in sight, 

 these fruits were left till frost killed the vines. 



No apparent difficulty was experienced in crossing golden 

 custard with crookneck ; and pistils of each could be fertilized 

 with pollen of its own kind and from the same plants, but pollen 

 of golden custard would not act on pistils of crookneck. Facts 

 of this nature seemed to indicate that the difficulty lay, not with 

 poor pollen in either case, nor with poor pistils, but rather in the 

 way they were combined. 



(2.) Histological studies. 



This feature of the work was begun by a study of dry pollen, 

 pollen in fluid mounts, and germinating pollen grains. In this 

 work all study was comparative. Pollen of crookneck and 

 golden custard was taken to the laboratory and examined with 

 high and low power objectives, with grains in dry and fluid 

 mounts ; but in size, shape and surface markings the pollen of 

 the two varieties was precisely alike. Pollen grains of the 

 squashes do not germinate readily in artificial media, and because 

 of this fact a study of germinating pollen was attended with 

 poor success. A careful examination of the male elements of the 

 squashes adds nothing to the solution of the problem. 



